Damn solid advice MikeOne of the most efficient ways to remove stuck or corroded items seems very counter-productive.
This knowledge is from over 21 years as an aircraft specialist in the USAF.
Here it is.
If you believe the thing you are removing has a corrosive or mechanical lock, then before attempting removal or loosening, tighten it.
I don't mean lean on it and smoke it down
What I mean is to move it an almost imperceptible amount to break the bind that has formed.
By going inward first, you save stresses on the removal side of the fastener, the fitting or whatever else you are attempting.
Less chance of the bit climbing out or the flares stripping.
An example of this was a young man named Aaron who wanted to call a machinist to remove 32 stuck fasteners on an F-15.
I told him I would remove each one for a beer and he agreed. At the 24th he stopped me and asked if he could try again. I said sure, but if he didn't know how I was doing it he would be wasting his time.
Aaron described what he observed and pressed on, successfully removing the other screws.
He trained his co workers on his new skill and the incidents of stripped screws and use of a screw jack almost disappeared.
Use a back up wrench with your strong hand if possible. Hold it perfectly still and loosen the flare nut with your weak hand keeping in line with the fitting. Nothing should break or strip